<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        var car = {
            name:'汽车',
            run:function(){
                console.log('兜风');
            }
        }
        //给原有属性添加 新的属性
        
        Object.defineProperties(car,{
            size:{

                value:'50w',
                configurable:true,//可以删除
                writable:true,//可以修改
                enumerable:true//可以枚举


            }
        })

        console.log(car);
    </script>
</body>
</html>